Grinding machine



P 1936- c. s. CUSHMAN I 2,055,404

' GRINDING MACHINE Filed Feb. 15, 1934 Patented Sept. 22, 1936 GRINDING MACHINE Charles S. Cushman, Barre, Vt., assignor to The Cushman Company, Barre, Vt.

Application February 15, 1934, Serial No. 711,426 3 Claims. (Cl. 51126) This invention relates to grinding machines of the type used particularly for grinding fiat surfaces and wherein the entire machine is sus-. pended in such a manner that the grinding wheel may be moved over the surface to be ground.

Certain machines of this type are arranged with a horizontal frame with a motor at one end and the grinding wheel at the other end, the frame being suspended from a crane or hoist at a point on the frame which will effect a desired balance between the motor and grinding wheel. In such devices, pressure of the grinding wheel on the surface to be ground is effected manually in some cases and this requires the exertion of considerable strength resulting in much fatigue to the operator. In other cases, the pressure is obtained by attaching weights to the end of the frame carrying the grinding wheel. This is a clumsy and undesirable expedient and renders it difficult to remove the wheel from the surface as is necessary for testing and inspection at more or less frequent intervals.

One important object of the present invention is to provide novel means, in connection with grinding devices of this type, whereby desired pressure of a grinding wheel on a surface may be effected without the addition of weights or the exertion of manual force to urge the grinding wheel against the surface.

A second important object of the invention is to provide a novel suspension arrangement for the frame of such a grinding device whereby the point of suspension may be shifted longitudinally 0f the frame so that the motor and grinding wheel ends may be unbalanced to produce the desired pressure effect of the wheel on the surface to be ground.

In machines of this class, the operator is comwco monl stationed at the grinding wheel so that he may move the wheel over the surface to be ground.

A third important object of the invention is to provide means operable from the grinding wheel 45 end of the frame for shifting the point of suspension longitudinally of the frame.

With the above and other objects in view, the invention consists in general of certain novel details of contruction and combinations of parts 50 hereinafter fully described, illustrated in the accompanying drawing, and specifically claimed.

In the accompanying drawing, like characters of reference indicate like parts in the several views, and 55 Figure 1 is a side elevation of a grinding machine constructed in accordance with this invention.

I Figure 2 is an enlarged section on the line 2-2 of Figure 1.

Figure 3 is a section on the line 3-3 of Fig- 5, ure 2.

Figure 4 is an enlarged section on the line 44 of Figure 1.

i In the embodiment of the invention shown in the drawing there is provided a pair of spaced 10 and parallel upper frame bars II! which are intended to assume a substantially longitudinal position during the operation of the device. Hangers H depend from the bars adjacent their ends and are braced to the bars by diagonal 15 braces [2. The bars ID are preferably angle irons each having one leg disposed vertically and the other legs projecting toward each other from the tops of the vertical legs but spaced to pro vide a slot l3. 20

.Secured to the lower ends of the hangers II is a tube l4 which extends parallel to the bars 10 and at one end projects well beyond the corresponding ends of the bars l0 and a bearing bracket or yoke I5 is fixed to the extremity of 25 this end. The arms of this yoke are arranged vertically, one above the other, to support a vertical shaft l6 which carries at its lower end a universal joint I! supporting a chuck l8 wherein is mounted a grinding wheel I9. On the shaft l6 0 is a fixed bevel gear 20 wherewith meshes a bevel gear 2! fixed on a shaft 22 journalled in the tube I 4 and projecting from the rear end thereof to carry a gear 23. A motor 24 is suspended beneath the tube and is provided with a pinion 25 35 meshing with the gear 23.

The parts just described constitute the grinding device which is suspended in the novel manner now to be described. A trolley body 26, of fiat plate-like form, projects through the slot I3 and carries at its upper end a fork 21 having its arms connected by a pin 28 for engagement by the hook 29 of any desired form of hoist. Through the lower end of the plate 26 extends a shaft 3!] on which are trolley wheels 31 engaging beneath the horizontal legs of the members I 0. As will be seen from Figure 2, these horizontal legs are positioned between the wheels 3| and the forked head 21. These parts thus form a suspension trolley and the frame members I!) form the rails for this trolley.

In order to adjust the trolley on its rails, the yoke l5 carries bearing brackets 32 wherein is journalled a shaft 33 having a sprocket 34 fixed thereon between the brackets 32. A crank handle is fixed to one end of the shaft 33. A chain 36 is trained around the sprocket 34 and has its ends connected to opposite ends of the trolley by means of cables 36a and 36b, idler pulleys 31 being provided at each end of the pair of bars l0 so that each cable is properly guided in its path. The crank handle 35 is arranged so that it may be conveniently grasped by one hand of the operator while his other hand is used to hold the handle 38 by which the wheel is guided over the surface being ground. By means of this arrangement rotation of the sprocket 34 in one direction or the other will correspondingly move the trolley forwardly or backwardly on the frame.

Obviously, rearward movement of the trolley will lengthen the distance between the grinding wheel and the point of suspension of the device so that the wheel will press against the surface with greater force than when the trolley is in forward position. It is obvious that the proportions of the parts may be made such as to obtain any desired pressure effects. For instance, the parts may be so arranged as to weight that a forward position of the trolley will rock the frame to'lift the grinding wheel. It will also be noted that all manipulation of the trolley is effected without the operator moving from his place at the grinding wheel. 7

There has thus been provided a simple and efficient device of the kind described and for the purpose specified. 7

It is obvious the changes may be made in the form and construction of the invention without departing from the material principles involved. It is not, therefore, desired to confine the invention to the exact form herein shown and described, but it is desired to include all such as properly come within the scope of the appended claims.

If desired, a guard casing 20 may be mounted around the gears 20 and 2i, with its ends secured to thebight portion of the yoke l5.

What is claimed is:

1. In a grinding machine, a grinding wheel, a motor driving said wheel, a horizontal frame carrying said motor and wheel at opposite ends and including a pair of spaced frame members forming trolley rails extending longitudinally of the frame, a trolley frame having a laterally expanded and forked head above said rails and a narrow body extending down between said rails, a pin extending across the forked head to form means for receiving a' suspension means, a single shaft extending transversely through the body, trolley wheels on opposite ends of said shaft bearing against the under sides of said rails whereby to rockably support the frame, and means adjacent the grinding wheel to cause rocking movement of the frame and operatively connected to the trolley body to move the rails with respect to the trolley wheels.

2. In a grinding machine, a trolley, a frame resting upon and supported by the trolley for rocking and longitudinal movement with respect thereto, a grinding wheel and a motor for driving the wheel on the frame at opposite sides of the trolley, and manually operable means for moving the frame longitudinally with respect to the trolley to cause rocking movement of the frame. 7

3. Ina grinding machine, a tro1ley, a frame supported by the trolley for rocking and longitudinal movement with respect thereto, a grinding wheel and a motor for driving the wheel on the frame at opposite sides of the trolley, and manually operable means for moving the frame longitudinally with respect to the trolley to cause rocking movement of the frame, said means including a sprocket revolvably mounted on said, frame adjacent said wheel, a crank for rotating said sprocket and a chain trained around said sprocket with its ends secured to opposite sides of the trolley.

CHARLES S. CUSHMAN. 

